/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.hash;

import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An abstract implementation of {@link Hasher}, which only requires subtypes to implement {@link
 * #putByte}. Subtypes may provide more efficient implementations, however.
 *
 * @author Dimitris Andreou
 */
@CanIgnoreReturnValue
@ElementTypesAreNonnullByDefault
abstract class AbstractHasher implements Hasher
{
    @Override
    public final Hasher putBoolean(boolean b)
    {
        return putByte(b ? (byte) 1 : (byte) 0);
    }

    @Override
    public final Hasher putDouble(double d)
    {
        return putLong(Double.doubleToRawLongBits(d));
    }

    @Override
    public final Hasher putFloat(float f)
    {
        return putInt(Float.floatToRawIntBits(f));
    }

    @Override
    public Hasher putUnencodedChars(CharSequence charSequence)
    {
        for (int i = 0, len = charSequence.length(); i < len; i++)
        {
            putChar(charSequence.charAt(i));
        }
        return this;
    }

    @Override
    public Hasher putString(CharSequence charSequence, Charset charset)
    {
        return putBytes(charSequence.toString().getBytes(charset));
    }

    @Override
    public Hasher putBytes(byte[] bytes)
    {
        return putBytes(bytes, 0, bytes.length);
    }

    @Override
    public Hasher putBytes(byte[] bytes, int off, int len)
    {
        Preconditions.checkPositionIndexes(off, off + len, bytes.length);
        for (int i = 0; i < len; i++)
        {
            putByte(bytes[off + i]);
        }
        return this;
    }

    @Override
    public Hasher putBytes(ByteBuffer b)
    {
        if (b.hasArray())
        {
            putBytes(b.array(), b.arrayOffset() + b.position(), b.remaining());
            Java8Compatibility.position(b, b.limit());
        }
        else
        {
            for (int remaining = b.remaining(); remaining > 0; remaining--)
            {
                putByte(b.get());
            }
        }
        return this;
    }

    @Override
    public Hasher putShort(short s)
    {
        putByte((byte) s);
        putByte((byte) (s >>> 8));
        return this;
    }

    @Override
    public Hasher putInt(int i)
    {
        putByte((byte) i);
        putByte((byte) (i >>> 8));
        putByte((byte) (i >>> 16));
        putByte((byte) (i >>> 24));
        return this;
    }

    @Override
    public Hasher putLong(long l)
    {
        for (int i = 0; i < 64; i += 8)
        {
            putByte((byte) (l >>> i));
        }
        return this;
    }

    @Override
    public Hasher putChar(char c)
    {
        putByte((byte) c);
        putByte((byte) (c >>> 8));
        return this;
    }

    @Override
    public <T extends @Nullable Object> Hasher putObject(
            @ParametricNullness T instance, Funnel<? super T> funnel)
    {
        funnel.funnel(instance, this);
        return this;
    }
}
